Radio system



June 29 1926.

o. G; M cAA RADIO SYSTEM Filed Jam- 192s Patented June 29, 1926.

UNITED STATES PATENT OFFICE.

DAVID G. MCCAA, 0F LANCASTER, PENNElYLVANIA, ASSIGNO-R T0 THEELEGTRIG AP- PARATUS G01, OF IPAljtKESBURG, FENNSYL'V'ANIA, A CORPORATION OF PENNSYL- VAN IA.

RADIO SYSTEM.

Application fi led January 19, 1925. Serial No. 3,281.

My invention relates to the reception of high or radio frequency energy, without in terference or disturbance due to other high or radio frequency energy produced artificially or by natural electricity as static atmospherics, etc., in systems in which the energy is transmitted either through the natural media or over a conductor or conductors extending between transmitting and receiving stations, for purposes of effecting receiving. stations controls or signals which may be either telegraphic or telephonic.

In some of its aspects my present inven* tion is of the character disclosed and claimed in my prior application Serial No. 722,246, filed June 25, 1924.

As in the aforesaid application, it is characteristic of my present invention that there is effected clear or sharp differentiation in the reception of signals between signal-- representing energy of low amplitude notwithstanding simultaneous existence of disturbing oscillations of high amplitude,

In accordance with my present inven tion, the frequency of the energy which it is desired should be excluded or reduced in effect and represented by oscillations set up by static or other natural electricity is caused to differ from, preferably to be lower than, the frequency of the energy which it is desired shall be received, and a signal-translating circuit, normally absorbing substantially no energy of either the desired or undesired oscillations, is caused to absorb energy of the desired oscillations and translate it into a control or signal in response to change in the natural period of the path or circuit which absorbs the energy from the natural media, such change in natural period being effected by energy of signal frequency derived. from that part of the absorption path or circuit utilized in effecting change of its natural period.

Further in accordance with my invention, the energy of signal frequency so derived from the absorption path or circuit is amplified, more particularly by regenerative action of a thermionic tube, for effecting a change in the natural period of the absorption path or circuit.

Further in accordance with my invention, there are included in the absorption path or circuit inductances in parallel with each other and preferably of materially differen't magnitudes, the inductance of lesser magnitude preferably utilized for coupling to the signal-translating circuit and the larger inductance comprising a pair of serially related in-ductances, preferably of different magnitudes, the smaller of said last named inductances coupled to the input circuit of a thermionic amplifier, preferably a regenerative amplifier, and the larger of said last named inductances coupled tothe output circuit of said'amplifier in such sense that the counter electro-motive-force of said larger inductance for signal frequency is changed, thereby changing the natural period of the absorption circuit or path; and more particularly, the sense of coupling of said larger inductance to the output circuit of the amplifier is in such sense for signal frequency less than static frequency that the magnitude of said larger inductance is decreased, or increased in case the signal frequency is higher than the static frequency.

Further in accordance with my invention, I provide in association with an inductive reactance a highly selective reactive system, as a regenerative amplifying system, for effecting with the inductive reactance'a combin ation which with sharpness or high selectivity effects marked changes in the currents traversing the inductive reactancei Myinvention resides in the method and apparatus of the character hereinafter described and claimed.

For an understanding of my method, and for an illustration of some of the various forms my apparatus may take, reference is to be had to the accompanying drawing, in which:

Fig. l is a diagrammatic view of radio receiving apparatus embodying my invention.

Fig. 2 is a diagrammatic view of a modified form of apparatus embodying my in vention.

Referring to Fig. 1, A represents generically any absorption structure of ar'adio receiving system, either an open antenna path or, if desired, a closed circuit or loop, and broadly any circuit or path receiving energy directly from the natural media or more or less remotely coupled to such a circuit or path; and A may represent alsoa' conductor system extending between transmitting and receiving stations as utilized, for example, in high frequency or carrier wave conductor systems. For brevity, however, my invention will be described in connection with radio receiving systems utilized for'any purposes, such as control of movements of ships or aircraft, of picture ormotion picture apparatus, or signaling. apparatus in general, including telegraphic and telephonic signals, it being understood that the translating instrument T, hereinafter referred to, representsgenerically any translating instrument, as a telephone or a control instrument of any character.

In the path between the antenna Aand earth or counter-capacity E are included the variable tuning condenser C, which may be omitted if suitable or "desirable, and the primaries P, P The secondary S is oppositely inductively afiected by the primaries P and P whereby'the circuit of the secondary S is not to any substantial degree affected by oscillations of any frequency simultaneously traversing the primaries P and P when the switch 8, in shunt to the primary P is in open position indicated.

The secondary S is connected in the in put or grid circuit, of a thermionic tube V, which may be utilized either as the first stage of a series of radio frequency amplifiers, or, as indicated, as a detector. The

tube 'Vcomprises the anode a, grid g, andcathode or filament f. In series with the secondary S is the variable inductance or variometer L,- both shunted bythe tuning condenser C and between a terminal of the latter and the grid 9 is included the usual grid condenser K shunted by the grid leak resistance 0-. In the anode circuit is the sourceof current B and the signal-translating instrument T, which may be a telephone or any other control, instrument, or which may be the primary of the first of one or more stages of audio frequency amplification.

As thus far described, the receiving circuit may be utilized forsparl; or wave train telegraphy or continuous wavetelephony. However, if utilized for continuous wave telegraphy, there may be included in the grid circuit of the. tube V a coil 1 inductively coupled to the coil 2 in circuit with the source of high frequency current 10 for well known heterodyne purposes.

In shunt to the primary P are the serially related inductances orv windings L and P The winding P is coupled to the inductance L in the input or grid circuit of the. radio frequency amplifier tube V The input circuit is tunable to the frequency of the oscillations representing the desired signalby thevariable condenser C or by varying L or both. The connection of the input circuit to the cathode or filament f is through the stabilizing resistance r connected across the battery 4., which supplies current for the filament I f. The positive side of the battery 4 or suitable terminal of the filament f is connected to earth or counter-capacity E. In the output or anode circuit is the source B inductance L? coupled to inductance L and shunted by the variable condenser C in long wave systems, the condenser C may be in shunt to the two; coils P and P and when varied may be used to tune the absorption or antenna path to the frequency of the desired signal. The circuit of the secondary S is similarly tuned to the frequency of the desired signal waves by varying the inductance L or condenser C or both, the inductance of the secondary S and of L preferably greatly predominating over the capacity C for effecting high selectivity to the desired frequency. The switch 8 is then opened, bringinginto the absorption or antenna path or circuit the inductances L and P in series with each other and in shunt to P Under these circumstances, due to the increased inductance in the antenna path, it

is detuned with respect to the frequency of the desired oscillations or signal, and the frequencyor predominant frequency of the oscillations set up in the antenna path by static, atmospheric or other disturbing elec trical effects is lower than the frequency of the desired oscillations, and the decrement of the static or undesired oscillations is decreased because of'the addition of inductance, and in consequence, oscillations of undesired frequency are more readily excluded from the circuit tuned to the frequency of the desired oscillations.

With the switch 8 open as aforesaid, both static and signal oscillations have substantially no effect upon the circuit of the secondary S, because of its reverse couplings to the primaries P and P and there would be no effect upon the instrument T except for utilization of auxiliary means about to be described.

With the switch '8 open, which is the normal position for operation of the system, the reactance of the branch I of the absorption circuit or path to both signal and static oscillations is materially or very much less than the reactance of that branch containing the inductances L and]? in series witheach other. In consequence, the greater part of both the signal and static oscillatory energy flows throughthe branch P anda 211 Psmaller portion through the branch- It is desired, however, to increase the re act-ance of the branch D, P for signal frequency to great degree, and to lesser degree for static frequency. This may be accom-' plished by in effect reducing the effective reactance of the inductance L in its branch. This is accomplished by impressing upon the tuned input circuit of the tube V oscillations of signal frequency traversing, the coil P The tube V with its input and output circuits so coupled as to effect substantial degree of regenerative action, as by the coupling effected by the capacity betweenthe grid 9 and anode a, materially amplifies the oscillations of signal frequency innpressed upon its input circuit, causing in its output circuit a highly amplified current of signal frequency, the increased energy of amplification being derived from the source B The highly amplified oscillations of sig-- nal frequency then inductively affect the coil L which is coupled in such sense to L that the counter electro-motive-force of'the coil L for signal frequency is substantially completely annulled, though it is not completely annulled for static frequency, par- 7 ticularly due to difference in amplitude between the strong static and weak signal oscillations. Upon such decrease of reactance of L for signal frequency, the ampli tude of the'oscillations of signal frequency in the branch 11 ,1 has now increased, correspondingly diminishing the amplitude of energy of signal frequency in the coil P with the result that the secondary S is now predominatingly influenced by, signal frequency by the primary P, though the effect upon the secondary S by static oscillations in the primaries P, P still remains more nearly equal, with the result that in the signal-translating circuit, enhanced by the tuning of the input circuit of the tube V, signal energy greatly predominates over static 'energ with the result that in the translating instrument T weak energy is readily distinguished notwithstanding the existence of relatively strong static. The inductive effect at signal frequency of'the coil L upon coil'L does not materially or so largely decrease the reactance or counter electro-mOtiveforce of the coil L with respect to the different or static frequency, and therefore the static energy in the coil P remains inore'nea'rly What it was originally.

It is interesting to observe that that setting of the condenser G which tunes the absorption path to the signal frequency when switch s is closed also serves to tune the absorption path to signal frequency when the switch 8' is open and the coil L is inductively influencing the coil L at signal frequency.

The aforesaid annullment or great decrease of reactance of the coil: L for signal frequency, aseffected by the amplified sig the reactance of L decreases for signal 1 frequency, current of signal frequency in P increases in amplitude, causing relatively further or increased amplification by the tube V and increased inductive effect of L upon L until a substantially saturated or stable state is attained.

In case itisdesired that the frequency of the static oscillations shall be higher than the signal frequency, with the switch s open the antenna or absorption path is tuned to" a frequency higher than the signal frequency. In this case the switch .8 is leftopen during the operation of the system. However, the sense of coupling of L to L is reversed in this case, with the result that the reactance of L as influenced by L at signal frequency is materially increased, the sense of coupling of P to L remaining as it wasin the first case described. Because. of the increase of reactance of L at signal frequency, greater energy of signal frequency is forced to traverse the coil P, which coil in this instance at signal frequency predominates over P in influencing S and the signal-translating circuit.

In the case where the'signal frequency is higher than the static frequency, in which case the reactance of L at signal frequency is to be annulled, there are two paths through which energy of signal frequency may reach the input circuit of the tube V One of these paths is through the coupling L L through the capacity between anode and grid of the tube V and the other is through the coupling P L the latter coupling opposing the effect of the coupling L L Inthe' secondcase, where the signal frequency is lower than the static frequency, and the reactance of'winding L is to be increased, the coupling L L assists the coupling P, L in transferring energy of signal frequency to the input circuit of the tube V In both cases it is preferred that the coupling between L and L be loose, while the coupling between P? and L may be either loose or close, but preferably close.

The arrangement of Fig. 2 is generically the same as that of Fig. 1. However, in shunt to the coil P is utilized the coil L inductively coupled to the coil L a portion of vvhich is in the anode circuit and another portion of which is in the input circuit of.

In the arrangementsof both Figs. 1 and 2 above described, the amplification, and particularly the regenerative amplification, of

the signal energy as effected by the tube V1, effects high selectivity of the signal frequen cy inthe branch L P of Fig. 1, or inthe branch L of Fig. 2. This high selectivity effects a highly selectivelow reactance system for the signal frequencyin shunt, Which system is in shunt to the coil P For the sakeof brevity in. the appended claims, the term signal is employed generically to include signals offany character, including telegraphic and telephonic signals, and any other analogous efi'ect, including controls; and the term static is generally employed to include static and other natural electrical effects and also other effects having artificial origin such as are caused or represented by waves or oscillations other than thoserepresenting the desired signal or-control. i

lVhat I claim, is: V a 7 a 1'. In the reception of radio signals, the method which comprises receiving the signal energy in a path including inductances and having a natural periodrlifi'ering from the period of the received oscillations, and changing thenatural period of said path by dividing the energy of oscillations between said inductances in said path, and changing the reactive effect of one of said inductances by amplifying the oscillationenergy traversing said one of saidinductances;

2. in the reception of radio signals, the method which comprisesreceiving the signal energy in a path including inductances and having a natural period differing from the period of the received oscillations, and changingthe natural period of said pathby dividing the energyfof.oscillations between said inductances in said path, and changing the reactive effect of one of said inductances by regeneratively amplifyingthe oscillation energy traversing said-one of said nductancesa V r a 3. In the reception of radio signals in a system comprising a path for receiving the signal energy, said path having branches including, respectively,inductance and a plurality of inductances, said path having a natural period differing from the period of the Again, the energy of signal frequency received oscillations, the method which comprises changing the natural period of said path bydividing the oscillation energy between saidbranches, amplifying the oscillatron energy traversing one of theinductances of one of said branches, ,and impressing the,- ampl hed energy upon the other inductance tweensaid branches, regeneratively amplilying the oscillation energy traversing one of the inductances of one of said branches, andyimpressing the amplified energy upon the: other inductanceof said one of said branches. c, a p

1 v 5. In the reception of radio signals in a system comprising a path for receiving the signal energy, said path having in series therein inductances in parallel with each other, the method which comprises amplifying thev signal oscillations traversing one of said inductances, and reducing the reactive effect of said one of said inductances by the amplified oscillations, and thereby decreasing theamount'of signal energy in the other of said inductances. V

6. In the receptionof radio signals in a systenrcomprising a path for receiving the signal energy, said path having in series therein inductances in parallel with each other, the method Which comprises regeneratively amplifying the signal oscillations traversing one of ,Said inductances, and reducing the reactive effect of said one ofsaid inductances by the amplified oscillations, and thereby decreasing the amount of signal energy in the other ofsaid inductances.

7 For the reduction of the effect ofstatic in the reception of signals in a system comprising a receivingpath having a natural periodditl'ering from the period of the sig nal oscillations, said path including inductances, and a signal circuit normally subjected equally and oppositely to thesignal and static oscillations, the method Which-comprises dividing the signal energy between said inductances, subjecting said signal circuit to the oscillations traversing one of said inductances, and amplifying the signal energy in another of said 'inductances to decrease its reactance to the signal energy.

8; The method of changingthe relative magnitudes of alternating current energy traversing inductances in parallel With each other, which comprises amplifying the en .ergy in one of said inductances to change its reactance to said energy.

CPA

9. The method of changing the relative magnitudes of alternating current energy traversing inductances in parallel With each other, which comprises regeneratively amplifying the energy in one of said inductances to change its reactance to said energy.

10. The combination With a path having inductances in parallel therein, of means for am li'fying the energy traversing one of sai inductances to vary its reactance to said energy.

11. The combination With a path having inductances in parallel therein, of means for selectively amplifying the energy traversing one of said inductances to vary its reactance to said energy.

12. The combination With a path having inductances in parallel therein, of means for regeneratively am lifying the energy traversing one of saic inductances to vary its reactance to said energy.

13. A receiving system comprising a path traversed by signal and static oscillations and having a natural period difl'ering from the period of the signal oscillations, a plurality of inductances in parallel With each other in said path, a signal circuit influenced by one of said inductances, and means for amplifying the energy in another of said inductances to change its reactance to said energy.

14. A receiving system comprising a path traversed by signal and static oscillations and having a natural period differing from the period of the signal oscillations, a plurality of inductances in parallel With each other in said path, a signal circuit influenced by one of said inductances, and means for regeneratively amplifying the energy in another of said inductances to change its reactance to said energy.

15. A receiving system comprising a path traversed by signal and static oscillations and having a natural period diiiering from the period of the signal oscillations, an inductance in said path, a signal'translating circuit influenced by said inductance, a plurality of inductances between which and said first named inductance signal energy divides, and regenerative amplifying means comprising input and output circuits inductively related, respectively, to said plurality of inductances,

16. A receiving system comprising a path traversed by signal and static oscillations and havinga natural period differing from the period of the signal oscillations, a signal-translating circuit, inductances in said path normally equally and oppositely influencing said circuit when said inductances are traversed by signal and static oscillations, and means for changing the ratio of the influences of static and signal oscillations between which and one of said first named inductances oscillatory energy divides, and means for amplifying the energy traversing said last named inductance for effecting a change of its reactance to the energy traversing it.

17. A receiving system comprising a path traversed by signal and static oscillations and having a natural period differing from the period of the signal oscillations, a signaltranslating circuit, inductances in said path normally equally and oppositely influencing said circuit When said inductances are traversed by signal and static oscillations, and means for changing the ratio of the influences of static and signal oscillations upon said circuit comprising an inductance between Which and one of said first named inductances oscillatory energy divides, and

means for regeneratively amplifying the energy traversing said last named inductance for effecting a change of its reactance to th energy traversing it.

18. A radio receiving system comprising a path traversed by signal and static oscilla tions and having a natural period difiering from the period of the signal oscillations, said path including branches, inductances in said branches, and means for changing the natural period of said path comprising means for changing the combined reactance oi: said inductances in said branches, said means comprising means for amplifying the oscillation energy traversing oneot said inductances, and means for impressing the amplified energy upon that branch including said one of said inductances.

19. A radio receiving system comprising a path traversed by signal and static oscillations and having a natural period differing from the period of the signal oscillations, a signal-translating circuit, a coupling for impressing signal and static oscillations upon said signal-translating circuit, a magnetic coupling comprising an inductance for impressing signal and static oscillations upon said signaLtranslating circuit in opposition to said first named coupling, and means for changing the ratio of the energies impressed upon said signaLtranslating circuit by said couplings comprising a branch path between which and said inductance the received oscillatory energy divides, and means for changing the reactance of said branch, sald last named means comprising means for am V pli'fying the oscillatory energy in said branch, and means for impressing the am plilied oscillatory energy upon said branch.

In testimony whereof I have hereunto affixed my signature this 13th day of January,

DAVID G. MoGAA. 

